Teenaged terror hits four to upstage Milan's Honda
Sassuolo's forward Domenico Berardi celebrates after scoring against AS Roma during their Serie A football match in Rome's Olympic Stadium on November 10, 2013
Japan international Honda, signed on a free transfer from CSKA Moscow, came off the bench for Massimiliano Allegri's side 20 minutes into the second half.
By that time, the damage had been done although Honda came close to helping reduce arrears for the struggling Serie A giants when a header came off the post late in the second half.
Robinho gave Milan a ninth-minute lead when he ran on to Nigel De Jong's ball after the Dutch midfielder and Bryan Cristante had dispossessed Raman Chibsah to beat Gianluca Pegolo with a low angled strike at the keeper's far post.
The visitors were 2-0 up only four minutes later when Mario Balotelli beat Pegolo with an angled strike to send Milan on their way to what appeared to be an easy three points.
Sassuolo, however, had other ideas.
Eusebio Di Francesco's side had succumbed to a 7-0 reverse at home to Inter Milan early in the season but showed great resolve to reduce their two-goal deficit within 13 minutes.
There was a hint of offside about Berardi's opener when he ran in behind the defence on the quarter hour to beat Christian Abbiati from a tight angle.
However Berardi's second was a fine demonstration of individual skills and sheer determination.
The striker collected in midfield, shook off one challenge, and then dismissed another in the area to turn and beat Abbiati with a sharp, angled strike.
Berardi completed his hat-trick on 41 minutes, nicking in ahead of Urby Emanuelson to leave Abbiati with no chance by first-timing Reto Ziegler's pacy cross from the left past the 'keeper.
The Sassuolo striker stunned Milan with his fourth of the game and 11th of the season two minutes after the restart when he bundled home from close range.
Allegri saw the warning signs and made a double substitution, Honda replacing Robinho and Riccardo Montolivo replacing Antonio Nocernino.
Honda found himself in a scoring position moments later but was spurned and then saw a header from a cross on the left blocked by Pegolo.
Seven minutes from time, Honda struck the post with a first-time curling effort from the edge of the area and although the rebound fell to Giampaolo Pazzini, Pegolo did well to block the striker from close range.
Milan were given a glimmer of hope five minutes from the finish when Montolivo collected De Jong's ball in midfield and struck a long-distance drive which beat Pegolo low at his far post
The visitors should have levelled three minutes from time but after Balotelli's header at the back post was punched out by Pegolo, Kaka followed up by sending the rebound against the crossbar.